NA50 is '-' but miassassemled contigs are show in icarus

[Unaimend]

So Icarus shows that there two super long misassembled contigs
.

But the NA50 for this specific reference is -. Could you explain why this is the case? Also why do I get a NGA50 value if the NA50 value is '-'

is the reason that when aligning to the combined reference it aligned to a different one then the "real" reference and thus could not be used again?

Thank you very much for your time